Mary:--A slight correction in terminology...The tube you are referring to is really a dip tube. It is the function of the dip tube to channel the incoming cold water to the bottom of the tank for heating. There are no moving parts to make noise associated with this tube. My guess is that there is a partially opened cold water feed stop supplying the water heater.often times the washer on this stop will vibrate and sound like a machine gun or scream like a Banshee. Try opening the supply valve to the water heater WIDE OPEN and see if that doesn't solve the problem. If you can determine that it is the valve that is createing the noise...change the washer or stem if the screw is corroded off. Lots of luck...Bud